Tags: Star.
S Persei is a red supergiant or hypergiant located in the Double Cluster in Perseus north of the cluster NGC 869. It is a representative of the semiregular variables whose periods of variation are subject to more irregularities than those of Mira variable red supergiants. Many of the visually bright (5th – 7th magnitude) variable stars belong to this class of semiregulars as these stars are extremely large and luminous and hence visible across long distances.